1. Field of the Invention
The invention relates to programmable timing devices for microprocessor systems.
2. Brief Description of the Prior Art
Integrated circuit microprocessors, especially MOS LSI microprocessors, have recently been widely implemented on a single semiconductor chip at economical costs. Such integrated circuit microprocessor chips have provided the foundation for low cost microcomputers when combined with LSI interface adaptors and memory chips. For example, see Applicant's issued U.S. Pat. Nos. 3,962,682 "Split Low Order Internal Address Bus for Microprocessor"; 3,979,730 "Interface Adaptor Having Control Register"; 4,004,283 "Multiple Interrupt Microprocessor System", and 3,975,712 "Asynchronous Communication Interface Adaptor". Such systems provide great computing power at low cost, but thus far such systems have not provided a capability of conveniently generating programmable output waveforms or of measuring elapsed time intervals under program control or generating signals indicative of programmable time intervals.